Temporal Temperature: Infrared Thermometers


Understanding Temporal Temperature

Thermometers are an important tool for measuring the dimensions of your health. Body temperature can indicate illnesses like infection or fever or conditions like hypothermia and shock. The Industry for medical thermometers is expected to grow in the wake of COVID-19.

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Body temperature is the primary method of screening for entry to buildings, and many people opt to keep one at home to detect fever themselves. 

In particular, the non-contact thermometer industry is expected to reach 3.2 billion by 2025, as they are convenient for screening in public places.

By eliminating the need to probe someone's ear or mouth, they limit the potential for spreading COVID, generate no waste, and are simply more convenient, reporting body temperature within a few short seconds. 

Thermometer Basics

Types of Thermometer

In the 20th century, glass thermometers that used mercury to measure body temperature were commonly used. The dawn of digital devices has replaced toxic mercury thermometers with digital thermometers instead. In addition to not containing toxic metals, digital thermometry is faster, more durable, and reports more accurate temperature measurements than mercury thermometers.

These include oral thermometers, rectal thermometers, ear (tympanic) thermometers,  and infrared thermometers, usually used for armpit or forehead thermometry. Some newer thermometers even have sensors build into pacifiers.

Accuracy and its Importance

In healthcare, it's important to have an accurate temperature reading. Body temperature can help identify several illnesses, whether at home or in the emergency department.

An accurate reading that reports a change in temperature can be a crucial sign someone may be going into shock, indicate a pediatric fever and influence healthcare for that patient. 

Fever Temperatures: Accuracy and Comparison

Temperature comparisons by device

  • Oral: 99.5–99.9ºF --Usually considered the gold standard for temperature measurements
  • Rectal/Ear: 100.4–101ºF --These are located more internally, so they run a bit warmer than oral
  • Armpit (Axillary)/Forehead (Temporal): 98.4–99.3ºF --These are located externally and measure heat from the skin, so they run a bit cooler than the rest. 

Accuracy of Different Methods

Arguably the most common thermometry method is the oral thermometer. It's fast and accurate and non-invasive. While oral temperature is convenient for most people and gives an accurate reading, young children may be unwilling to tolerate the probe under their tongue, which can be uncomfortable while waiting for the beeps.

Instead, tympanic thermometers (named after the medical term for the eardrum) are often used for children. They detect infrared radiation inside the ear canal, yielding an accurate body temperature measurement.

They're often quicker than other thermometry methods and less uncomfortable, so they are ideal for checking a child's temperature.  The only drawback to ear thermometers is that large buildups of earwax can disrupt the measurement.

Lastly are rectal thermometers. It's unlikely you have these at home--they're usually reserved for hospitals and emergency departments. Naturally, a rectal thermometer reading is uncomfortable.

But a rectal temperature reading can be a reliable indicator of core body temperature in situations of reduced blood flow to the face and extremities, in cases of hypothermia or shock. 

What You Need to Know about Temporal Thermometers

Many newer thermometers work on the forehead by measuring the heat from the temporal artery. This is the large blood vessel that bulges out on people's foreheads when they're angry! It's an artery, which brings blood fresh from the heart, so temporal artery temperatures can often serve as a reliable indicator of core body temperature.

Zero Contact

The temporal artery traverses most of the forehead, to the heat it brings from your core can easily be detected all around your forehead. And since your forehead's tissue is rather thin, the heat emitted can be detected from a small distance. Several forehead thermometers have non-contact temporal scanners that can do just that and measure the infrared radiation an inch or so away from your skin. 

Ease of use

Because the forehead is a rather large surface, temporal artery thermometers are often the easiest way to take a temperature reading. The fact that they can be non-contact and still yield a fairly accurate temperating reading (so long as you measure below the hairline) makes them the most convenient type of thermometer.

Choosing a temporal thermometer

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FAQ

What is the normal temperature on the forehead?

Everyone's body temperature is different--some people naturally run a little cooler, some a little hot. Exercise, atmospheric temperature, and illnesses can influence your forehead's temperature. 

The normal forehead temperature is just slightly lower than oral temperature (98.6ºF) to within a degree of 97.6ºF is reasonable. 

Can you take your temperature on your temple?

The temples are you the corners of your face, at the far ends of your forehead. Directly on the forehead would be more accurate, but a good temporal thermometer will get a good reading even if applied to the temple. Just be sure it's below the hairline and directly on your skin. 

Is 99.4 temporal a fever?

It could be considered a mild fever. But it depends on the person. Some people run hot and feel fine. Some people may feel sick and lethargic at that temperature. And it's important to check if the temperature is consistently elevated--a small spike can happen in exercise or outside in hot weather. 

Do you add a degree for temporal temp?

Yes. Temporal temperature is just slightly lower than oral temperature, which is the gold standard. Adding a degree can offset this. 

What is normal skin temperature on forehead?

Normal forehead temperatures range from about 97.6 to 98.1ºF.

How do I use an infrared thermometer on my forehead?

Follow your specific thermometer's instructions, but in general, you apply the scanner to your forehead and hold. Most thermometers usually chime or beep when they're taken a temperature reading.